added correct server file

Dockerfile

@@ -0,0 +1,20 @@
+# Use an official Node.js runtime as the base image
+FROM node:14
+
+# Set the working directory in the container
+WORKDIR /app
+
+# Copy package.json and package-lock.json to the working directory
+COPY package*.json ./
+
+# Install project dependencies
+RUN npm install
+
+# Copy the application code to the working directory
+COPY . .
+
+# Expose the port on which the server is listening
+EXPOSE 3000
+
+# Start the server
+CMD [ "node", "app.js" ]

app.js

@@ -0,0 +1,11 @@
+const express = require('express');
+const app = express();
+
+app.get('/', (req, res) => {
+  res.send('Hello, World!');
+});
+
+const port = process.env.PORT || 3000;
+app.listen(port, () => {
+  console.log(`Server running on port ${port}`);
+});